Reciprocating spray gun carriage assembly for spray coating or like apparatus



Aug 16, 1966 T. N. BASKETT RECIPROCATING SPRAY GUN CARRIAGE ASSEMBLY FORSPRAY COATlNG OR LIKE APPARATUS 3 Sheets-Sheet 1 Filed June 29, 1964Theodor NBQSkeH .lil

Aug. 16, 1966 T. N. BASKETT REGIPROCATING SPRAY GUN CARRIAGE ASSEMBLYFOR SPRAY COATlNG OR LIKE APPARATUS 5 Sheets-Sheet 2 Theodore NBaskeHINVENTOR.

Filed June 29, 1.964

Aug. 16, 1966 T N. BASKETT 3,266,729

RECIPROCATING SPRAY GUN CARRIAGE ASSEMBLY FOR SPRAY COATING OR LIKEAPPARATUS Filed June 29, 1964 3 Sheets-Sheet 5 United States PatentRECTPRUCATENG SPRAY GUN CARRIAGE ASSEMBLY FQR STRAY QUATHNG 0R LIKEAPEARATUS Theodore N. Baskett, 9514 Portland Ave, Tacoma 44, Wash. FiledTune 29, 1964, Ser. No. 378,867 Claims. Cl. 239186) This inventionrelates to a reciprocating spray gun carriage assembly of the classemployed in spray coating and like apparatus. It particularly pertainsto a reciprocating spray gun carriage assembly for use in spray coatingpaints or adhesives on plywood, wood composition board or other sheetmaterial continuously passing a spray coating station on a conveyor.

It is the general object of the present invention to provide areciprocating spray gun carriage assembly for use in spray coating orlike apparatus and characterized by the following advantages:

1) Widely applicable to the spray coating of a diversity of work pieceswith diverse types of paint, glue and other coating materials.

(2) Highly eflicient and operable at a high production rate.

(3) Adjustable to accommodate coating materials of varying viscosity.

(4) Free from vibration.

(5) Stroke easily adjustable to suit different Widths of work pieces.

(6) Smooth acceleration and deceleration at any speed.

(7) Free from fouling of the carriage assembly mechanism by the sprayedmaterial.

(8) Free from explosion hazard even though the coating materialsemployed are highly flammable.

(9) Characterized by greatly reduced wear on moving parts.

(10) Light in weight, truly portable and requires little or no anchoringat its operating station.

(11) Stroke adjustable to any length or any position, i.e. left side,right side, or center, of work pieces passing the coating station.

(12) Spray gun instantly inactivatable when shutting down for anyreason, thereby preventing excessive damage to work pieces being coated.

(13) Amount of overspray can be adjusted to suit the viscosity of thecoating material.

(14) Can accommodate one or a plurality of guns working in overlappingpaths and adjustable, if desired, to spray in one direction of travelonly.

(15) Areas on which overspray can build up are kept :at a minimum,preventing accumulated overspray from loosening and falling on thecoated work.

(16) Running adjustments of stroke and spray gun operating periods canbe made.

(17) Eliminates inefficient, scotch-yoke type of reciprocating carriageassembly conventionally used in spray coating apparatus.

Generally stated, the reciprocating spray gun carriage assembly whichaccomplishes the foregoing and other objects of the invention comprisesa carriage track arranged suitably with reference to the work to becoated, as the work moves continuously past the coating station on anendless conveyor. A carriage is supported on the track. It, in turn, isprovided with means for mounting one or more spray guns.

Flexible, elongated, drive means, such as a length of chain reverselybent about a sprocket, is connected to the carriage substantiallyparallel to the track. Reversible motor means, preferably a pair ofsingle-acting, alternating, fluid-operated cylinders, are connected tothe drive means.

Patented August 16, 1966 Of the foregoing elements, the track, carriage,flexible drive, and motor means are assembled within a cabinet toprotect them from overspray. Where a pneumatic drive is employed, it isexhausted Within the cabinet, providing a pressurized environment. Thespray gun mounting means extends outside the cabinet so that the gunsonly are exposed to the spray coating environment.

Suitable control means .for the motor means are so positioned that theyare contacted by the carriage after a predetermined travel, thereuponreversing the motors and securing a reciprocating motion of the carriageacross the work. The control means are adjustable as required to adjustthe carriage travel to the width of various work pieces and also tochange the location of spraying selectively to coat the right, left, orcentral portions of the work.

Also actuatable by the carriage is spray gun control means. This issynchronized with the control means for the motor so that the spray gunsare turned on and off as they pass across and beyond the work. Thisoccurs each time the direction of motion of the carriage is changed.Depending upon the viscosity of the coating material, greater or lesseroverspray time periods are re quired, and these periods may be adjusted.

Preferably all of the operating units of the assembly, i.e. the sprayguns, the drive motor for the carriage, the controls for the drive motorand the controls for the spray gun, are fluid operated so that they maybe incorporated in a single fluid drive system. This simplifies theconstruction and eliminates the necessity for providing electriccircuits, which would increase the danger of exploding the highlyflammable solvents often present in coating materials.

Considering the foregoing in greater detail and with particularreference to the drawings, wherein:

FIG. 1 is an end elevation, partly in section, of the herein describedreciprocating spray gun carriage assembly, illustrated in conjunctionwith an endless conveyor moving work pieces past the spray coatingstation;

FIG. 2 is a view in side elevation of the assembly of FIG. 1;

FIG. 3 is a longitudinal, sectional view, taken along line 3-3 of FIG.2;

FIG. 4 is a transverse sectional view taken along line 44 of FIG. 1;

FIG. 5 is an enlarged detail plan view illustrating particularly thedrive motor control means, looking in the direction of the arrows ofline 5-5 of PEG. 4;

FIG. 6 is an enlarged detail plan view and FIG. 7 is an enlarged detailview in side elevation, looking in the direction of the arrows of line7-7 of FIG. 4, of the control means for controlling the operation of thespray guns mounted on the herein described reciprocating spray guncarriage assembly; and

FIG. 8 is a schematic view illustrating :an integrated fluid circuit,specifically a pneumatic circuit, which may be employed to actuate thecomponents of the herein described apparatus.

Referring to the drawings:

FIGS. 1 and 2 illustrate a typical environment in which thereciprocating spray gun carriage assembly of the invention is to beemployed. An endless conveyor 16 moving in a guideway 12 carries plywoodpanels, sheets of wood composition board, or other work pieces 14, pastthe spray coating station.

At this station, is located the spray coating apparatfis, supportedabove the conveyor on standards '16.

The apparatus is housed in an elongated housing, indicated generally at20, and substantially wider than the work pieces to be sprayed. As shownin FIGS. 3 and 4, housing 20 is fabricated from a pair of side plates22,

24, a composite bottom plate formed of two slightly spaced-apart,angularly-bent pieces 26 bolted to the side plates and provided withflexible curtain strips 28; a composite top plate composed of a pair ofspaced, angularlybent plates 36 bolted to the top of side plates 22, 24,and a pair of end plates 32, 34. The central, longitudinallyextendingslot present between bottom plates 26 provides a guideway in which worksthe spray gun support, while the corresponding central,longitudinally-extending slot between top plates 30 provides a guidewayin which works the suppont arm for the spray gun control mechanism, aswill appear hereinafter.

Housed within housing is a reciprocating spray gun carriage driveassembly which, in the illustrated form of the invention, is geared toprovide a relatively high rate of carriage travel at a relatively lowdrive motor speed.

To this end there are provided two cooperating car- 'riage assemblies,the first of which is driven relatively slowly and which carries boththe control means for the drive motor and the control means for thespray guns, and the second of which moves at a relatively high speed andcarries the spray guns themselves.

The first, or control-mounting carriage assembly, is supported on a pairof spaced track bars 40, FIGS. 3 and 4. These are rectangular in crosssection and extend substantially parallel to each other and to thelongitudinal direction of housing 20, but at right angles to the worktraveling on conveyor '10. The track bars preferably are arranged toprovide two pairs of angled side faces, 42, 44, each of which provides atracking surface. The bars thus are reversible to provide fresh trackingsurfaces after a period of use.

The first control carriage assembly comprises a fiat body 46 havingangled side faces 48, 50 on both sides. Extending normal to side face 48is a shaft 52 which mounts a wheel 56. Extending normal to face 50 is ashaft 54 on which is journalled a wheel 58. Similar shafts and wheelsare provided on the opposite side of the bar.

The horizontal axis of carriage body 46 is aligned with the horizontalaxes of track bars 40. The angular relationship between side faces 42,44 of the track bars and side faces 48, 50 of the carriage body is suchthat wheels 56, 58 of the carriage track on side surfaces 42, 44 of thetrack bars, thus providing a sturdy, vibration-proof mounting in whichwear is kept at a minimum.

Carriage body 46 mounts a suppont arm 60, which extends upwardly throughthe guideway between top plates of the cabinet. The arms supports thevalve which controls the spray guns, as will be described hereinafer.

The underside of carriage body 46 mounts a downwardly and angularlyextending cam arm 62 which supports a cam 64 having oppositely beveledcam surfaces, also to be described hereinafter.

The second, or spray gun mounting carriage assembly, moves on track bars70. These extend the entire length of housing 20. They are spaced apart,parallel to each other, and directly below track bars 40. Like thelatter, track bars 70 are arranged at an angle to present side faces 72,74.

Supported on track bars 70 is a carriage assembly comprising a body 76having angled side faces 78, 80. Extending substantial normal to therespective side faces are a first axle 82 on which is journalled wheel84, and a second axle 86 on which is journalled wheel 88.

Carriage body 76 is aligned with track bars 70 and the angularrelationship between the side faces is such that wheels 84, 88 of thecarriage track on side faces 72, 74 of the track bars. As pointed out inconnection with track bars 40, track bars 70 may be reversed 180 after aperiod of use, thus providing fresh tracking surfaces.

Afiixed to, and extending downwardly from, the undersurface of carriagebody 76 is a support arm 90. This arm works in the sealed slot presentbetween between bottom plates 26 of cabinet 20. It supports the spraygun assembly,

The latter includes a manifold 92 and, spaced below the manifold, acrossarm 94 on which are mounted one or more spray guns 96 supplied withcoating material and compressed air through flexible conduits in theusual manner.

The drive by which control-mounting carriage 46 and spray gun-mountingcarriage '76 are reciprocated at differential rates is illustratedparticularly in FIGS. 3, 4 and 8. This drive, as well as its controlsystem and the spray guns mounted on the apparatus preferably all arepneumatically operated and are described as such. However, it is to beunderstood that other types of drives, for example, hydraulic drives,may be substituted.

As seen in FIG. 3, the motive power is supplied by a pair ofalternating, single acting, long stroke, pneumatic cylinders 100, 102.The rearward ends of the cylinders are supported on a bracket 104; theforward ends, by a support plate 106. The cylinders are connected inseries through a conduit 108, so that the air exhausted from the workingcylinder must pass through the idle cylinder before being vented. Thisslows down the action of the cylinder and produces a stroke of moreuniform speed.

The piston rod of cylinder 100 is coupled to a connecting arm 112 whichconnects it to control carriage 46. It also is coupled to one end of aflexible drive member, e.g. a length of chain 114. The piston rod 116 ofcylinder 102 is connected to the other end of chain 114.

The chain, in turn, engages a sprocket 118 fixed to a shaft 120journalled in bearings 122, 124. As cylinders 1G0, 102 alternately areextended and retracted, drive chain 114 is reciprocated endwise at aspeed and stroke commensurate with the speed and stroke of thecylinders. This drives correspondingly control carriage 46 connected tothe piston rod of cylinder 100 through connecting link 11-2.

Spray gun carriage 76 also is driven by cylinders 100, 102, but at anaccelerated rate.

Keyed to the same shaft 120 as is sprocket 118 is a second sprocketwhich may be, for example, twice the diameter of sprocket 118. Sprocket'130 mounts one end of an endless chain 132, the other end of which ismounted on idler sprocket 134 at the far end of the apparatus. Carriage76 is fastened to chain .132 by means of a coupling 136. Accordingly,chain 134 reciprocates with chain 114, but at twice the rate and withtwice the stroke. This moves spray gun carriage 76 and the spray gunscarried thereby between the extreme dotted line positions of FIG. 1.

The control means for regulating the stroke of spray gun carriage 76 isillustrated in FIGS. 4 and 5.

A horizontal bracket extends lengthwise of the housing. Adjustablymounted on the bracket by means of bolts 142 are a pair of spaced valveactuators. These may be pneumatic bleeder valves 144, which control theaction of a master valve connected directly to the cylinder. Contactbuttons 146 of the valves are positioned for actuation by cam 64 on theend of arm 62 and serve to control the alternate reciprocation ofcylinders 100, 102, both as to length and location of stroke.

Thus, by setting valve actuators 144 at any spaced interval alongbracket 140, the stroke of the cylinders will match accordingly and anydesired area of the work may be sprayed with guns 96.

Spray gun control means also are provided. These energize andde-energize the spray gun synchronously with the reciprocation of spraygun carriage 76. This presents a considerable problem, since it isdesirable to overspray sufficiently to cover the work completely, butinsufiiciently to waste the coating material and create offensivedeposits.

The extent of overspraying in turn is dependent upon the viscosity ofthe coating material. More viscous materials cause the spray gun to beless responsive to the control which shuts it on and off. For thisreason it is necessary to provide spray gun control means which areadjustable to suit coating materials of varying viscosity. The controlmechanism which I have devised to meet this need is illustratedparticularly in FIGS. 4, 6 and 7. Mounted on arm 60 supported on controlcarriage 46 is a spool-type pilot air valve 150. The ends of the spoolextend outwardly from the body thereof and terminate in cam rollers 152.

Cooperating with cam rollers 152 are cam elements indicated generally at154. There are two pairs of these elements, one pair being locatedadjacent each terminus of control carriage 46.

The cam elements are mounted on elongated brackets 156 extending theentire length of travel of carriage 46. The cam elements each comprise abase 158, a support arm 160 and, pivoted to the support arm by bolt 162,a triangular cam plate 164.

The cam plates of each pair are arranged opposite to each other. As aconsequence, as valve 150 passes by the members of one pair it will beactuated by one of the cam plates, altering the operation of the spraygun. However, as it passes the oppositely arranged cam plate of thepair, the cam plate will swing to the dotted line position of FIGS. 6and 7 in which it is inoperative. Then when the direction of motion ofthe carriage is reversed, the reverse action takes place. The cam platepreviously inoperative becomes operative, and that previously operativebecomes inoperative.

Accordingly, when a very viscous coating material is being sprayed, thecam members of each pair may be separated by an appreciable distance.The cam member which is innermost with respect to the work is so placedthat the spray gun is de-energized substantially before it reaches theend of its stroke. However, because of the viscous character of thematerial, the spraying will continue until the end of the stroke. Thecam plate furthest removed from the work is passed by and withoutfunction.

Upon reversal of the carriage, the latter cam plate is energized,actuating the spray gun. Again because of the viscosity of the coatingmaterial, actuation of the spray gun does not result immediately inemanation of coating material. Rather, there is a lag until the edge ofthe work is reached, whereupon the spray is initiated. In this motionthe innermost cam plate tilts upwardly and is idle.

On the other hand, when thin, non-viscous coating materials areemployed, cam plates 164 may be substantially opposite each other, thestarting and stopping of the spray being substantially instantaneous.

FIG. 8 illustrates an integrated, pneumatic system 'by which all of theunits of the herein described apparatus may be controlled and operated.

Air from a source of compressed air passes through a filter 170, anoiler 172, a pressure gauge 174 and a check valve 176.

Valves 144 which control the spray guns may be bleeder valves,cooperating with a pressurized, balancedspool, four-way pneumatic valve178. When bleeder valves 144 are actuated by cam 64, a pressuredifferential is established in four-way valve 178. This causes it tomove and energize one or the other of cylinders 100, 102. The inactivecylinder exhausts its air through valve 178, as well as through athrottle valve 180 and a shutoff valve 182. There thus is provided aneffective way of starting and stopping the spray gun carriage, as wellas for controlling its speed.

Similarly, when pilot valve 150 is energized by contact with cams 154,it energizes a quick-dump" pneumatic valve 184 which instantaneouslyloads and unloads manifold 92, controlling the spray guns.

OPERATION Briefly summarized, the operation of the herein describedreciprocating spray gun carriage is as follows:

First, the entire unit is stationed over the plywood panel 14 or otherwork passing the coating station on conveyor 10. Bleeder valves 144 arepositioned to regulate the stroke of cylinders 100, 102 to the desiredlateral location and length. Pilot valve actuators 154 are set todetermine the on-off positions of the spray guns with reversal ofmotion, their position being determined by the length of stroke ofcylinders 100, 102 and the viscosity of the coating material.

Valve 182 is opened. This starts the apparatus. Valve 1813 is regulatedto control the speed by controlling the flow of air exhausted fromalternately reciprocating cylinders 100, 162.

As the cylinders reciprocate they reciprocate endwise drive chain 114,rotating small sprocket 118 and hence large sprocket on common shaft120. Large sprocket 130 drives endless chain 132 at an accelerated ratedetermined by the differential diameters of the two sprockets.

Spray gun carriage 76 connected to chain 132 moves rapidly back andforth across the work. However, to insure better control, less wear andsmoother operation, control carriage 46, driven directly by piston rod110 of cylinder 100, moves at a greatly reduced rate. Arm 62 and cam 64carried thereby strike first one and then the other of bleeder valves144, reversing the motion of the apparatus in accordance with theirsetting.

Pilot valve also carried by carriage 46 progressively strikes spacedcams 154, alternately turning on and shutting off the air suppliedthrough dump valve 184 and manifold 92 to spray guns 96. The spacingbetween the members of each valve pair determines an overruncommensurate with the viscosity of the coating material, for mosteflicient use of the latter.

Running adjustments of bleeder'valves 144 and cam units 154 can be madeat any time. Also, the air from the system is exhausted within theenclosing housing, pressurizing the latter and preventing entrance ofcoating materials. Still further since electrical circuits areeliminated completely, the hazard of explosion when using coatingmaterials containing volatile solvents also is eliminated.

It accordingly will be seen that there is provided an apparatus in whichthe several objects of this invention are achieved and which is welladapted to meet the conditions of practical use.

It is to be understood that the form of my invention herein shown anddescribed is to be taken as a preferred example of the same and thatvarious changes in the shape, size and arrangement of parts may beresorted to without departing from the spirit of my invention or thescope of the subjoined claims.

Having thus described my invention, I claim:

1. In spray coating or like apparatus a reciprocating spray gun assemblycomprising:

(a) carriage track means arranged operatively with reference to workbeing coated,

(b) a carriage supported on the track means,

(c) spray gun mounting means on the carriage,

(d) flexible, elongated drive means connected to the carriage and havingspaced ends,

(e) reversible fluid operated motor means having a pair of piston rodsmovable simultaneously in opposite directions and each connected to adifferent one of the spaced ends of the drive means,

(f) motor control means actuatable periodically by the carriage toreverse the mot-or means after a predetermined travel of the carriage,and

(g) spray gun control means actuable by the carriage and synchronizedwith the motor means for altering the operation of the spray gun at apredetermined time with reference to the reversal of the motor means.

2. The apparatus of claim 1 wherein the carriage includes a horizontalbody having angled side edges with wheels mounted thereon parallelthereto, and wherein the track means comprises elongated bars havingangled side edges, the bars being aligned horizontally with the body ofthe carriage and the upper and lower wheels of the carriage trackingrespectively on the upper and lower angled side edges of the tracks.

3. The assembly of claim 1 including housing means enclosing the trackmeans carriage, motor means and drive means, the housing means having alongitudinal slot along its bottom wall, and a support arm extendingthrough the slot and connected at its inner end to the carriage and atits outer end to the spray gun mounting means, and wherein the motormeans comprise a reversible pneumatic motor exhausting inside thehousing means, thereby maintaining positive air pressure within the samefor preventing ingress of sprayed material to the interior of thehousing means.

4. The assembly of claim 1 wherein the drive means comprises a reverselyarranged length of chain engaging a sprocket and wherein the reversiblemotor means comprises a pair of fluid operated cylinders connected oneto each end of the chain.

5. The assembly of claim 1 wherein the drive means comprises a length ofchain reversely arranged on a sprocket and wherein the reversible motormeans comprises a pair of pneumatic cylinders connected one to each endof the chain.

6. The assembly of claim 1 wherein the drive means comprises a length ofchain reversely arranged on a sprocket and wherein the reversible mot-ormeans comprises a pair of single-acting, alternating pneumatic cylindersinterconnected to exhaust the air from the working cylinder through thenon-working cylinder.

7. The assembly of claim 1 wherein the drive means comprises a rotatablymounted shaft, sprockets of different diameters keyed to the shaft, alength of chain reversely engaging the smaller of the sprockets, a pairof alternating single-acting, fluid operated cylinders connected one toeach end of the chain, an endless chain engaging the larger of thesprockets, and connecting means on the endless chain for connecting thechain to the carriage.

8. The assembly of claim 1 wherein the spray gun is a pneumaticallyoperated spray gun and the spray gun control means comprisescam-operated valve means mounted on the carriage and in a pneumaticcircuit with the spray gun the valve means comprises a sliding spool airvalve having on each end an external cam roller, and wherein two pairsof cams are adjustably mounted spaced from each other in the path oftravel of the carriage; each cam including a cam plate arranged atworking angle with reference to the cam roller, a support arm, and meansfor pivotally supporting the cam plate on the support arm; the camplates being oppositely arranged with respect to each other, whereby toinactivate one cam plate of each pair upon traversal of the carriage inits first direction and to inactivate the other cam plate of each pairupon traversal of the carriage in its reverse direction.

References Cited by the Examiner UNITED STATES PATENTS 3,027,095 3/1962Paasche 239187 3,041,999 7/1962 Bogshan 239-186 3,172,606 3/1965Reynolds et a1. 239-18 FOREIGN PATENTS 601,617 7/1960 Canada.

EVERETT W. KIRBY, Primary Examiner-

1. IN SPRAY COATING OR LIKE APPARATUS A RECIPROCATING SPRAY GUN ASSEMBLYCOMPRISING: (A) CARRIAGE TRACK MEANS ARRANGED OPERATIVELY WITH REFERENCETO WORK BEING COATED, (B) A CARRIAGE SUPPORTED ON THE TRACK MEANS, (C)SPRAY GUN MOUNTING MEANS ON THE CARRIAGE, (D) FLEXIBLE, ELONGATED DRIVEMEANS CONNECTED TO THE CARRIAGE AND HAVING SPACED ENDS, (E) REVERSIBLEFLUID OPERATED MOTOR MEANS HAVING A PAIR OF PISTON RODS MOVABLESIMULTANEOUSLY IN OPPOSITE DIRECTIONS AND EACH CONNECTED TO A DIFFERENTONE OF THE SPACED ENDS OF THE DRIVE MEANS, (F) MOTOR CONTROL MEANSACTUATABLE PERIODICALLY BY THE CARRIAGE TO REVERSE THE MOTOR MEANS AFTERA PREDETERMINED TRAVEL OF THE CARRIAGE, AND (G) SPRAY GUN CONTROL MEANSACTUABLE BY THE CARRIAGE AND SYNCHRONIZED WITH THE MOTOR MEANS FORALTERING THE OPERATION OF THE SPRAY GUN AT A PREDETERMINED TIME WITHREFERENCE TO THE REVERSAL OF THE MOTOR MEANS.